An aviation turbomachine conventionally comprises a compressor, a combustion chamber and a turbine. The role of the turbine is to rotate the compressor while drawing a portion of the pressure energy from the hot gases leaving the combustion chamber and transforming it into mechanical energy.
An axial compressor consists of a rotating portion, the rotor, a fixed portion, the stator, and a shroud, the casing, the stator and the casing being fixedly attached to one another. The rotor comprises a drum consisting of an assembly of several disks to which movable blades are attached in a circumferential array. The stator consists of a plurality of blades attached to the casing or to rings in a circumferential array. Each array of fixed blades of the stator, called stator blades, forms a synchronizing ring. An array of movable blades and an array of fixed blades form a compressor stage.
In a compressor, to optimize the efficiency of the turbomachine and the surge margin depending on the speed, one or more arrays of stator blades may have a variable pitch, that is to say that the angle of attack of these blades varies according to the flight conditions.